Electron discharge apparatus



Aug. 2, 1938. c. A. BIELING ELECTRON DISCHARGE APPARATUS Filed Nov. 20,1936 INVENTOR C.A.B/EL/NG BY 04mm 6. M

A TTORNEY Patented Aug. 2, 1938 PATENT OFFICE 2,125,280 ELECTRONDISCHARGE APPARATUS Carl A. Bieling, Westfield, N. 1., assignor to BellTelephone Laboratories, York, N. Y., a corporation of New YorkIncorporated, New

Application November 20, 1936, Serial No. 111,813

12 Claims. (Cl. 250-275) This invention relates to electron dischargeapparatus and more particularly to such apparatus adapted to generateultra high frequency oscillations, for example, oscillations offrequencies of the order of 3000 kilocycles or less.

One object of this invention is to decrease the electron transit timesin high frequency electron discharge devices whereby the operating rangeof such devices is increased.

Another object of this invention is to increase and to make uniform theelectron velocities in electron discharge devices.

In one illustrative embodiment of this invention, an electron dischargedevice comprises a cup-shaped anode, which may constitute a portion ofthe enclosing vessel of the device, and a cathode within the anode andpositioned rela tively remote from the base thereof. The cathode isencompassed by a cylindrical metallic screen or shield electrode open atits ends and extending to adjacent the base of the anode. The shieldelectrode is encompassed in turn by an auxiliary or ionization electrodehaving a perforated or mesh portion between the base of the anode andthe end of the shield electrode thereadjacent. The enclosing vessel ofthe device may have an ionizable medium therein, such as an inert gas,for example argon or a mixture of gases or of a gas and mercury, at alow pressure.

The auxiliary electrode is operated at a positive potential with respectto the cathode sufficient to produce ionization by electron bombardmentof the gaseous medium, the current between the cathode and the auxiliaryelectrode being confined by theshield electrode to paths around the endof the shield electrode in juxtaposition to the base of the anode. Theionization of the gaseous medium produces an abundance of free electronswithin the cavity .or chamber defined by the shield electrode and theperforated or mesh portion of the auxiliary electrode and theseelectrons constitute the source of energy for the high frequency fieldof the device.

The cathode is positioned relatively remote from the perforated or meshportion of the auxiliary electrode and the base of the anode is dis- Theinvention and the various features thereof will be understood moreclearly from the following detailed description with reference to theaccompanying drawing in which:

Fig. 1 is an elevational view in perspective of an electron dischargedevice constructed in accordance with this invention, a portion of theinclosing vessel and of the internal electrodes being broken away toshow the internal structure more clearly; and

Fig. 2 is a diagrammatic view of an ultra high frequency transmitterincluding an electron discharge device of the construction shown in Fig.1.

Referring now to the drawing, the embodiment of this invention thereinillustrated comprises an electron discharge device including anenclosing vessel having a bulbous vitreous portion In and a cup-shapedmetallic portion H serving as the anode of the device. The metallicportion H is provided with a flaring flange l2 hermetically sealed tothe vitreous portion Ill and also with an inwardly extending annularflange l3 forming a seating member upon which other electrodes of thedevice are supported.

Mounted upon the flange I3 is an auxiliary or ionization electrodeincluding a flange It seated upon an annular insulating spacer or washerI5, for example of a ceramic material, in turn seated upon the flangel3, and an elongated cylindrical or sleeve portion l6 extending toadjacent the" base ll of the cup-shaped anode ll. Preferably thecylindrical portion is imperforate and disposed coaxially within theanode. The end of the cylindrical or sleeve portion IS in juxtapositionto the base I I has extending thereacross a perforated disc member 3,such as a mesh screen, disposed parallel to the base I! of the anode.The auxiliary electrode may be associated with an external circuitthrough a leading-in conductor l9 sealed in the vitreous portion I0 andextending therefrom.

An elongated, imperforate, cylindrical shield or screen electrode 20 isdisposed coaxially with the auxiliary electrode and extends to adjacentthe perforated disc portion [8 thereof. The shield or screen electrode20 is provided with an annular flange 2| which is seated upon aninsulating spacer or washer 22 in turn seated upon the annular flangeIt. The flanges 2|v and I4 and the insulating spacers l5 and 22 may besecurely held in position upon the flange l3 by a locking ring 23threaded to the metallic portion of the enclosing vessel and bearingagainst an insulating washer 24.

Disposed within the shield or screen electrode 25 encloses a heaterfilament 26 encased in. ceramic material 21 and provided with leading-H'20 is a cathode comprising a cup-shaped metallic,

anode and coated with a thermionic material;

suchas alkaline earth metal oxides. 'Ehe shell in conductors 23. One ofthe conductors 28 is connected to the shell 25 by an integral tab 29extending from the shell, and also to the shield electrode 20 byametallic strap 3|! so that during operation of the device the cathodeshell 25 and the shield or screen electrode are at substantially thesame potential.

The enclosing vessel III, II or the device may have an ionizableatmosphere therein, such as a filling of an inert gas at low pressure.For ex.- ample, the vessel may have a filling of argon at a pressure of0.1 millimeter of mercury or less, or of a mixture of, gases or of a asand mercury.

The QSDacing between the base I! of the anode and the perforated orscreen portion l8 of the auxiliary electrode is small in comparison tothe mean free path of the molecules of the gaseous medium. The spacingbetween the cathode 25 and the perforated or screen portion I8preferably is relatively large to provide a long distance path betweenthe cathode and the auxiliary electrode.

The electron; discharge device maybe incorporated, as shown in ;Fig. 2,in a transmission systern, including coaxial tubular conductors El and32*. The outer conductor 3| encompasses the electron discharge deviceand' the Edevice is properly positioned within this conductor by acylindrical metallic sleeve 33,: spaced from the conductor 3| by ametallic annulus 34 and from the cylindrical portion, of the anode by aband of insulation 35. The anode |!,|'l may be maintained at a positivepotential with respect to the outerlconductor 3| by a suitable source"such as a battery 39. The inner conductor 32 encompasses extensions ofthe leading-in conductors 26 andJB for the heater filament 26 and theauxiliary electrode l6, l8. The eifective length of thecoaxial system,and hence the tuning thereof, may be varied by a slidable condensermember including a metallic disc 36 contacting with the outer conductor3|, asecond metallic disc 31 contacting with the inner conductor 32 andan insulating disc 38 spacing the metallic discs 36 and 31 and suitablysecured thereto. 7

The heater filament 26 maybe energized from a Editable source, such as abattery 40 and a suitable potential, positive with respect to theoathode, may be applied to the auxiliary electrode |6, |8 bya sourcesuch asra battery 4 The potential applied to the auxiliary electrode issufficient to produce ionization of; the gaseous medium in the producean arc trode. Because of the close spacing of the perforated portion l8and the base I! or the anode,

the region therebetween operates as though no gaseous medium werepresent. The oscillations produced as above described are transmittedalong the coaxial conductors 3| and 3% to a suit-' able receiving orampiifying apparatt'n.

Inasmuch as the free electrons produced within the shield electrode 20are in a field of uniform potential with respect to thecathode, theywill travel to the anode at high and substantially uniform velocities.Furthermore, because of the increased velocities of the electrons, thetransmit times thereofawill be very smailso that the derlce may beoperated efliciently at extremely high frequencies. V

Devices oi the construction shown and described hereinabove may beoperated also without the ionizable medium within the enclosing vessel,in which case the auxiiiary electrode I6, l8 serves as an acceleratingelectrode to assure uniform mean velocities for the electrodes inflowing to the anode.

fithough a specific embodiment of the invention has been shown anddescribed, it will be understood that this embodiment is merelyillustrative and that various modifications may be made therein withoutdeparting from the scope and spirit of this invention as defined in theappended claims.

What is claimed is:

1. Electron discharge apparatus comprising an enclosing vessel having agaseous filling, a cathode, an anodehaving a portion remote 'fromesaid-said shield and having a cylindrical portion mounted coaxially withintion of said anode.

3. Electron discharge apparatus comprising a cathode, an elongatedcylindrical shield encompassing said cathode and having an openendremote therefrom, an anode having a portion in proximity to said openend, and'an auxiliary electrode encompassing said shield and having aperforate portion adjacent said open end.

4. Electron discharge apparatuscomprising a the cylindrical porcathode,a cup-shaped anode encompassing said cathode, an imperforate cylindricalshield electrode between said cathode and said anode and terminatingatone end adjacent thebase of said anode, and an auxiliary electrodehaving a portion encompassing said shieldmlectrode and a perforatedportion between said one end thereof and said base of said anode.

5. Electron discharge. apparatus comprising an enclosing vessel havingan ionizable atmosphere therein, an elongated cylindrical shield memberwithin said vessel, a planar cathode within said shield member andremote from one end thereof, means within said vessel electricallyconnecting said shield member to said cathode, an ionization electrodeoutside of said shield member, and an anode having a portion adjacentsaid one end of said shield member and substantially parallel to 6.Electron discharge apparatus comprising an enclosing vessel having agaseous filling at low pressure, a cathode, an auxiliaryelectrodeincluding an elongated cylindrical portion encompassing said cathodeand, a grid portion at one end of said cylindrical portion, animperforate cylindrical shield member between said cathode and saidauxiliary electrode and extending to adjacent said grid portion, meanselectrically connecting said shield member to said cathode, and an anodehaving a portion adjacent said grid portion.

'7. Electron discharge apparatus comprising an enclosing vessel havingan ionizable medium therein, a cathode within said vessel, an ionizationelectrode having a perforate portion remote from said cathode, a shieldmember within said ionization electrode, encompassing said cathode andterminating adjacent said perforate portion, and an anode having aportion adjacent said perforate portion and spaced therefrom a distancesmaller than the mean free path of the molecules of said ionizablemedium.

8. Electron discharge apparatus comprising an enclosing vessel having agas at low pressure therein, a cathode, an elongated cylindrical shieldencompassing said cathode and having an opening remote therefrom, ananode adjacent said opening, and an ionization electrode encompassingsaid shield and having a perforated portion between said opening andsaid anode and spaced from said anode a distance small in comparison tothe mean free path of the molecules of said gas.

9. Electron discharge apparatus comprising an anode having asubstantially plane portion, a cathode in alignment with said planeportion and remote therefrom, an ionizable medium between said cathodeand said anode, an imperiorate cylindrical shield encompassing saidcathode and extending to adjacent said plane portion, and an auxiliaryelectrode including a cylindrical member encircling said shield and agrid substantially parallel to said plane portion and spaced therefrom adistance small in comparison to the mean free path of the molecules ofsaid ionizable medium.

10. Electron discharge apparatus comprising an enclosing vesselincluding a cup-shaped metallic portion constituting an anode, saidanode having an internal flange, a cathode within said vessel and remotefrom the base of said anode, a cylindrical shield encompassing saidcathode and extending therefrom to adjacent said base, an auxiliaryelectrode having a cylindrical portion encompassing said shield and aperforated portion adjacent said base, and means insulatingly supportingsaid shield and said auxiliary electrode from said flange.

11. Electron discharge apparatus comprising a cathode, an anode having asurface opposite said cathode, a tubular shield member extending betweensaid anode and said cathode and having one end adjacent said anode, andan auxiliary electrode between said anode and said shield member, saidanode and said auxiliary electrode having coaxial cylindrical portionsdisposed one within the other.

12. Electron discharge apparatus comprising a cup-shaped anode, acathode within said anode and relatively remote from the base thereof,an elongated hollow shield encompassing said cathode and extendingtherefrom to immediately adjacent the base of said anode, an ionizablemedium in which said cathode and shield are immersed, and an auxiliaryelectrode having a cylindrical portion within and coaxial with saidanode and extending from said cathode to a point intermediate the baseof said anode and the end of the shield thereadiacent.

CARL A. BIELING.

